The appeal court, however, ruled that the sending of copies of data seized to the U.S. was unauthorized

A court in New Zealand has ruled that warrants used to search the homes of Megaupload founder Kim Dotcom and his colleague Bram van der Kolk were valid, but objected to the removal to the U.S. by the Federal Bureau of Investigation of copies of the electronic items seized.

The Court of Appeal of New Zealand ruled Wednesday that the warrants were defective in some respects, but the defects were not sufficient to treat them as "nullities."

A ruling against the validity of the warrants would have made it harder for the U.S. bid to extradite Dotcom, van der Kolk and two other colleagues to face charges in the U.S., as the evidence collected could have been called into question.

Dotcom and colleagues, and two companies including file-sharing site Megaupload, were indicted by a grand jury in the Eastern District of Virginia in January 2012, and charged with engaging in a racketeering conspiracy, conspiring to commit copyright infringement and money laundering, and two substantive counts of criminal copyright infringement, according to the U.S. Department of Justice.

On Jan. 20, 2012 the New Zealand police searched the homes of Dotcom and van der Kolk and seized more than 135 electronic items, including laptops, computers, portable hard drives, flash storage devices and servers, containing an estimated 150 terabytes of data, according to court records. The police also obtained warrants for the arrest of Dotcom and his three associates and they were arrested at the same time.

The search warrants were obtained at the request of the U.S. DOJ, which is seeking the extradition of Dotcom, van der Kolk and two other associates to face the charges of copyright infringement and money laundering in the U.S. District Court for the Eastern District of Virginia.

The respondents successfully challenged the validity of the search warrants and the removal of the clones from New Zealand in the High Court, which ruled that the warrants were invalid because they were not in sufficiently specific terms and that the removal of the clones of the data to the U.S. was in breach of directions.

Dotcom and the other respondents would have understood the nature and scope of the warrants, especially in light of their arrest warrants, which were not defective, and the explanations given to them by the police when the properties were searched, the appeal court ruled.

However, the sending of copies of electronic data seized at the homes was not authorized, as on Feb. 16, 2012 the solicitor-general directed the Commissioner of Police under that the items seized during the searches were to remain in the "custody and control" of the commissioner until further direction.

"Notwithstanding the Solicitor-General's direction, forensic clones of some of the electronic items seized during the searches were made by the FBI and taken by the FBI back to the United States in March 2012," the court observed.

The appeal court did not, however, provide any directions as to the return of the material provided to the FBI.

Dotcom's lawyer Ira Rothken said in a message on Twitter that the "legal team is reviewing the rulings made by the Court of Appeal and will likely seek leave to appeal to the Supreme Court."